Variable-speed power transmission.



J. G. P. THOMAS.

VARIABLE SPEED POWER TRANSMISSION.

APPLICATION FILED MAR. 1, 1913.

1,165,038. Patented Dec. 21, 1915.

5 SHEETSS HEET I.

My fi /aaw" J. G. P. THOMAS. VARIABLE SPEED POWER TRANSMISSION.-APPLICATION FILED run. I. ma.

1,165,038.- Patented Dec. 21, 1915.

5 SHEETS-SHEET 2.

"J. G. P. THOMAS.

VARIABLE SPEED POWER TRANSMISSION.

APPLICATION FILED MAR. 1, 191a.

Patented Dec. 21, 1915.

5 SHEETS-SHEET 3- I. G. P. THOMAS.

VARIABLE SPEED POWER TRANSMISSION.

APPLICATION FILED NHL 1. I9I3- 1,165,038. Pa te'nted Dec.21,1915.

5 SHEETSSIIEET 4.

Jf/amy J. G. P. THOMAS.

VARIABLE SPEED POWER TRANSMISSIQN. APPLICATION FILEDEMAR. h 1913.

1 165,038, Patented Dec. 21, 1915.

5 SHEETS$HEET 5.

/iv 'Lmmr v mission, ofwhich the following is a spcci JOHN G. P. THOMAS,OF CHISWICK, LONDON, ENGLAND.

VARIABLE-SPEED POWER TRANSMISSION.

Application filed March 1, 1313.

To all whom it may concern.

Be it known that I, JOHN GODFREY PARRY THOMAS, a subject of the King ofGreat Britain, residing at 21 Ennismore avenue, Chiswick. in the countyof London, England, have invented new and useful Improvements inVariable-Speed Power Transfication.

Certain prime motors, in particular internal combustion engines, runefficiently only at a particular speed, or speaking generally have amaximum efficiency at a particular speed for any given output. In

order to use such prime motors economically in the driving of variableloads, it is neces sary and usual to interconnect them with their loadshafts through means which permit variation of the speed ratio of themotor and shaft, and the driver in charge of the motor alters the speedratio according asthe torque calledfor at the load shaft varies.

The first purpose of the present invention is to enable the requiredvariations in speed ratio to be brought about automatically. To this endthe speed varying apparatus is made dependent upon the condition of thesystem so that the speed ratio automatically alters in the mannerrequired. to permit the prime motor to operate under the bestconditions. For many purposes, for instance for the driving ofvehicles,the range of variation of load may besuch that it is not practicable ordesirable to permit the prime motor always to exert its full power.

The invention-therefore further comprises means for altering thecondition of the prime motor Whichthe automatic apparatus tends tomaintain.

The invention is particularly applicable to rail motor cars-in which theprime motor is an internal combustion engine connected with the drivingwheels by means, such as the electromechanical transmission systemdescribed in my earlier United States Patent No. 948436, dated 8thFebruary 191.0, which permit variation of the speed ratio between theengine and the wheels. As it may not infrequently be desirable to havethe transmission system upon one vehicle controlled from anothervehicle, an electrical method of control is adopted. This comprises anelectric motor geared to the controlling-device which varies the speedratio, and a generator driven by the prime motor connected Specificationof Letters Patent.

Patented Dec. 21, 1915. Serial No. 751,618. i

in series with the controller motor with a battery in its circuitopposing it. It will be clear that the'controller,motor willbe putinaction whenever the voltage of the auxiliary generator exceeds or fallsbelow that of the battery, the battery voltage de- Figure 1 is adiagrammatic representation of the main parts of the system. Fig. 2 is adiagram of the electrical connections, Fig. 3 shows diagrammaticallycertaln mechanr cal connections. Figs. 4, 5 and 6 illustratemodifications of the electrical connections.

In the arrangement of Fig. 1 the prime motor is indicated as an internalcombustion engine 1 which is connected through an electromechanicaltransmission gear substantially like that described in my earlierspecification No. 948436 with a shaft 2 gearedto the road wheels of avehicle. An epicyclic gearing 3 connects the shaft of the prime motor onthe one hand to the shaft of an electrical machine 4 and on the otherhand to a shaft 5 which is normally coupled by the clutch -6 to theshaft 2 which carries the armature of an electrical machine 7. Afurtlierclutch 8 serves by joining the shaft 5 to the shaft of themachine 4 to put the gearing 3 out of action. This transmissionmechanism constitutes a means-whereby the speed of the shaft 2 may bevaried without alteration of the speed of'the prime motor 1. Suchvariation is effected by a suitable variation of the electricalconditions of the machines 4 and 7, the fields and armatures of whichare for this purpose joined to a controller 9 which in the usual wayinserts resistances in the circuits of the machines and generally makessuch connections as are required for the particular system of control.This controller is operated by the rotation of a gear wheel 10 upon itsshaft, each tooth in such gear wheel conveniently corresponding o onenotch Of thG-COIItIOIlGI.

For the purpose of the present invention, the controller 9 is operatedthrough its gear wheel 10 by a single tooth pinion 11 on the shaft ofthe small motor 12 which may-have permanent magnets or be excited fromany suitable source. A. suitable ratchet ll on the controller shaftengaged by a spring pressed stop 42 insures the controller moving acomplete notch at a time. The motor is'supplied with current from thearmature '13 of .a dynamo secured upon the shaft of the prime motor 1;but the circuit also includes a battery 14 which normally opposes thegenerator 13. There is also in the circuit a contact in the controller 9indicated in Fig. 2at 15. This contact is always made except when thecontroller 9 is in the neutral position and is therefore indicated asconsisting of an arm on the shaft of the con-' troller contacting withan interrupted circular contact. The field 16 of the generator 13 issupplied from any suitable source, for instance the battery 1 1, and iscontrolled by a rheostat 17 which constitutes the chief element of themaster controller. This master controller is more fully indicated inFig. 2

from which it will be apparent that movement 7 of the handle not onlyvaries the amount of the resistance 17 included in'the circuit of thefield 16, through the end insulated portion of the handle bridgingbetween the resistance-studs and a contact are, F but also in oneposition makes an independ-. ent contact 18,-between the other metallicportion of the handle and a stud,in parallel with the contact-15. Thefield circuit also includes a switch 21 which is operable by hand, sothat current is not uselessly taken from the battery when the engine isstopped.

Where the prime motor an internal combustion engine it may "be desirableto 4 make the control of the transmission gear affect also the controlof the prime motor so that the engine may not be run at a low speed withthe throttle wide open. For this purpose the carbureter throttle valve.19 may 4 be controlled for example by means of a solenoid 20.

It will easily be understood that the rotation of the motor 12 isdependent upon the existence of a difference of E. M. F. between thegenerator armature 13 and the battery 14. Supposing the system tobe innormal running condition, that is both the prime motor and the loadshaft in rotation, it is clear that at acertain speed of the prime motorthe E. M. F. ofthe armature 13 will exactly equal that of the battery 14and so long as that-condition is maintained the controller 9 will remainstationary. "If the speed of the load shaft should diminish,'for

trol device tends to maintain it.

shaft, and the motionof the controller will clearly continue until theprime motor has again attained its former speed, the load shaft however,rotating more, slowlys ln the event of the load shaft gaining in speedthe opposite effect would occur, in all cases the controller 9 beingsoshifted as to bring back'the prime motor to a particular speed, viz. thespeed at which the voltage of the armature 13 balances that of thebattery 14.

Under some circumstances it may be de-' sired to vary the'sneed at whichthe prime motor runs and at which the automatic con- Such variation iseffected by the aid of the master controller, which in actualconstruction may,

like the controller 9, resemble the controller described in my UnitedStates Patent No. 1005081 dated 3rd October 19-11. Theinser tion ofresistance in the circuit of the field 16 Will obviously diminish thevoltage of armature 13 for a given speed so that the prime motor Willneed to attain a higher speed before the voltage of the battery 14 isbalanced. At the instant when such a weakening of field 16 is broughtabout the battery Will overpower the generator and will operate thecontroller I) as above described so as to increase the speed ratio between the prime motor and the shaft 2 with the' result in this case thaton the cessation of the controller movement the prime motor will berotating at a higher speed at which it will thenceforward tend to bemaintained by the automatic operation of the apparatus.

It is highly undesirable to permit an in-' ternal combustion engine tobe run at a low speed with the carbureter throttle fully open. Toprevent this, the throttle is interconnected with the master controllerby means 'of the solenoid 20 which is shown as in the circuit of thefield 16. If this field is strengthened so as to cause the prime motor 1to run at a low speedthe solenoid 20 at-- with the exception that thethrottle control last above described-naturally applies only to systemshaving an internal combustion engine as prime motor. In general eachtransmission system will have its peculiar advantages which may bysuitable provision be retained with the automatic control abovedescribed. For instance where the prime motor is an internal combustionengine the transmission mechanism will preferably permit of the primemotor being run light, e. separated from the load shaft, and may alsoprovide for the automatic starting of the prime motor. By way ofillustration of the application of the invention in such cases thepeculiarities of its application to the transmission mechanismillustrated will now be described.

In the particular transmission mechanism illustrated the prime motor 1can be run light byreleasing the clutch 6; and it can be automaticallystarted in various ways,

for example by putting in the clutch 8 while the clutch G is out and'drivingthe machine 4: as a motor from the battery 14; or another sourceof supply. In order that the control by the apparatus described mayextend to these operations, the clutch 8 is interconnected with thecontroller 9 so that it is engaged only when the controller 9 is in oneof its extreme positions, 2'. 6. either the top speed position or theposition for starting the engine; and the clutch 6 is interconnectedwith both the controller 9 and the master controller 17 so as to be heldout by the controller 9 when it is in the engine starting position orthe next position (the position for running light) while when onceengaged the controller 9 is unable to operate it and it can be releasedonly by movement of the master controller to the second or first notch.These interconnections may be of various kinds. interconnection by meansof cams is shown.

The clutch 8 is joined through levers 22 and a rod 23 to a roller lyingin the path of a cam 24.- which is fast upon the shaft or axle of thecontroller 9 so as to be rotated when the controller .is turned. Theclutch 6 issimilarly connected through levers 25 and 26,. and rods 27.28 both to a roller in the path of a cam 29 on the shaft of controller 9and also to a roller in the path of a cam 30 onthe shaft of the mastercontroller 17 This drawing is but diagrammatic, but it may easily beseen that by suitable shaping of the respective cams the clutches can beheld out. or allowed to be put in at the appropriate times merely by therotation of the controller. is formed without sloping shoulders with theresult above indicated that once clutch 6 is engaged movement of thecontroller 9 cannot throw it out. 7 It is, however, equally possible tooperate the clutches bypower instead of by hand for example byelectromagnetic means. For instance Fig. 4 shows an electromagneticconnection between clutch 6 and the master controller 17. A

In Fig. 3 a mechanical It will be noted that cam 29 solenoid 31 actsdirectly or through any in Fig. 2); so that the movement of the mastercontroller from notch II to notch I though it increases the current inthe circuit of field'16 does not substantially alter the E. M. F. of thearmature 13 for a given speed. If the master controller is brought downto notch II from any higher notch the throttle will be very nearlyclosed and the field 16 will be brought up to full strength while theclutch 6 will be released. The strengthening of the field would tend tooperate controller 9 in such a fashion as to decrease the speed ratiobetween the prime motor and the load shaft; but this effect is nullifiedby the closing of the throttle. The condition of the throttle is suchthat it permits the engine to run light at a speed of say 100revolutions per min ute and 'at this speed with the field 16 at fullstrength the E. M. F. of the battery is greater than that of thearmature 13. Consequently the controller 9 will be rotated in thedirection required to increase the speed ratio between the prime motorand load shaft, but as the speed of the prime motor is is no longercurrent in the circuit of the If the master controller, is

machine 12. brought down to notch I the increase of current in thecircuit of field 16, while not further appreciably affecting the E. M.F. of armature 13, increases the attraction of solenoid 20 and causes itto completely close the throttle 19 so that the prime motor stops. Whenit has stoppedthere is no need to keep the throttle closed and no needto have a current flowing through the field 16 or solenoid 20; thecircuit may .therefore be broken by opening the hand switch 21.Obviously if desired this switch could be operated automatically. Forinstance the master controller may be built with an extra end notch asindicated at O in Fig. 4,'upon which the circuit of the field 16 isbroken.

Supposing the prime motor to have been running light, it is obvious thatthe auto matic control cannot recommence until the circuit of motor 12-is closed. It is for this reason that contact 18 is provided in parallelwith contact 15. This contact is made when the master controller isbrought to I notch III, and this same. action, while slightly weakeningthe field 16, opens the f throttle 19 and permits the clutch 6 toengage, always supposing the switch 21 has first been closed. The clutch6 does not at once engage being still held out by the controller 9. Thecondition of the throttle is begins running on the lowest running notch.The motion of the controller will continue until the speed of the primemotor is brought down to about 300 revolutions.

Ifthe prime motor has been completely stopped it is necessary first torestart-it. This can conveniently be done by the provision of an enginestarting notch on the controller 9 which should be beyond the neutralposition. Upon this engine starting notch the clutch 8 is engaged andtheclutch 6 disengaged while electrical circuits are made for drivingthe machine 4 as above "mentioned. To bring the controller 9 to thisnotch "after the engine has been stopped, it is suflicient to move themaster controller to notch III. The circuit of the motor. 12 is thenclosed and as the armature 13 is not rotating the battery 14 presentsthe only E. M. F. in the circuit. The controller 9 is therefore rotatedin the direction which on the higher notches increases the speed ratiobetween prime motorand load shaft. Hence the controller is rotatedbackward beyond the neutral position into the engine starting position.If the switch 21 has'been duly closed the engine starts and if themaster controller is kept on notch III will run up toward a speed of 500revolutions. In so doing it will cause armature 13 to overpower thebattery 14 and the further operation of the controller 9 will beeffected as above described. Should the switch 21 have been left open,as might happen with the arrangement of Fig. 2, the engine may not startbecause the throttle is wide open, the driver then has to return themaster'controller to notch I in order to close the switch andreco-mmence.

If desired a further notch could be provided between notchesII and IIIon the master controller which would enable the engine to run at anincreased speed with the clutch 6 still disengaged. Upon this notch thepower of the engine could be employed of the electrical machines forcharging the battery 14. This is illustrated by the notch II in Fig. 5.It will be noted that upon that' notch the controller 17 completes acontact 33 by which the generator 13 on the shaft of the prime motor isjoined through a suitable resistance across the battery 14 to charge it.It will be obvious that the controller could make any further necessarychanges in the field rheostat and so forth which might be necessary forany particular purpose.

Naturally the battery may be employed not only to start the engine andto work the controller but also through the conductors 40 to supply thelights on the vehicle, and the ignition of the engine.

It will be obvious that the throttle 19 might be interconnected with themaster controller mechanically instead of electrically, for instancesubstantially in the manner indicated for the clutches.

If electromagnetic clutches are used their circuits may readily becontrolled by contacts' in the respective controllers. In Fig. 6, 34indicates the winding of a magnetic clutch in the place ofclutch 8, and35 that of a magnetic clutch replacing clutch 6. The winding 34 isconnected across the battery 14 through a contact 36 in the'controller9. The winding 35 has in its circuit both a conthrough one tact 37 inthe controller 9, and in series with that a contact 38 in-the controller17. In the diagram of controller 9, A indicates the engine startingpositlon, E the neutral-position in which the controller rests when theapparatus is not working. D to L are the runmng notches corresponding todifferent connections in the controller by which different speeds areobtained from the electromechanical transmission mechanism; and M is thetop speed or direct drive. The clutch 8 should be engaged in the enginestarting position and on the top speed but at no other time; it will benoted that' the position and extent of the contact 36 fulfils thiscondition. The clutch 6 on the other hand has to be held out in theengine starting position and in the position for running light, andaccordingly the contact 37 does not extend to these positions. It doesextend, however, to a notch C beyond the lowest running notch, so thatthe clutch the transmission gear isshaft, variable speed powertransmission v mechanism interconnecting said prime motor and load.shaft, an electric generator driven by said prime motor, a battery anda motor in the circuit of said generator, and means operated by saidmotor varying the speed ratio of said power transmission mechanism.

2. In combination, a prime motor, a load shaft, variable speedelectromechanical power transmission mechanism interconnecting saidprime motor and load shaft, a controller for varying the speed ratio ofsaid mechanism, an electric generator driven by said prime motor, abattery and a motor in the circuit of said generator, and meansinterconnecting said motor and the controller.

3. In combination, a prime motor, a load shaft, variable speed powertransmission mechanism interconnecting said prime motor and load shaft,a generator driven by said prime motor, a motor and battery in thecircuit of said generator, the" battery opposing the generator, meansenabling said motor to vary the speed ratio of the transmissionmechanism, and means for altering the speed at which the generatorbalances the battery.

, 4:. In combination, a prime motor, a load shaft, variable speed powertransmission mechanism interconnecting said prime motor and load shaft,a generator driven by said prime motor and having a field winding, amotor and battery in the circuit of said generator, the battery opposingthe generator, means enabling said motor to vary the speed ratio of thetransmission mechanism, means for altering the speed at which thegenerator balances the battery, and means for varying the field of saidgenerator.

v5. In combination, a prime-motor, a load shaft, variable speed powertransmission mechanism interconnecting said prime motor and load shaft,a generator driven said prime motor, means operated bysaid generator forvarying the speed ratio of said power transmission mechanism so as tokeep the speed of the prime motor substantially constant, and means forvarying such speed of the prime motor.

6. Incombination, an internal combustion engine, a load shaft, variablespeed transmission mechanism interconnecting said engine and load shaft,means controlled by the' speed of said engine for varying the speedratio of said mechanism so as to keep the engine speed substantiallyconstant, means foraltering the speed at which the engine is maintained,and means for simultaneously operating the throttle of said engine.

.7. In combination, a prime motor, a load shaft, variable speedtransmission. mechanism interconnectin said prime motor and load shaft,control evices for automatically varying the speed ratio of saidtransmission mechanism so as to maintain the prime mo-'. tor atsubstantially constant. speed, and.

means for varying the speed at which said control devices tend tomaintain the prime,

motor.

8. In combination, an internal combustion engine, a load shaft, variablespeed transmission mechanism interconnecting said engine and load shaft,a controller for varying the speed ratio of said transmission mechanism,a generator driven by said engine, a battery and motor in the circuit ofsaid generator, connections between said motor and the controller, andmeans for altering simultaneously the condition of the prime motor andthe action of said generator, battery and motor for a given speed of theengine.

9. In combination, a prime motor, a load shaft, variable speed powertransmission mechanism interconnecting said prime motor and load shaft,a controller for varying the speed ratio of said mechanism, a generatordriven by the prime motor, a battery and motor in the circuit of saidgenerator, gearing connection between said motor and said controller, afield winding for said generator, and a rheostat controlling the currentthrough said field winding.

10. In combination, an internal combustion engine, a load shaft, avariable speed power transmission mechanism interconnecting said engineand load shaft, a controller for varying the speed ratio for saidmechanism, a generator driven by the engine, a battery and mdtor in thecircuit of said generator, gearing connection between said motor andsaid controller, a field winding for said generator, an electromagneticcontrolling device in series with said field winding and connected withthe throttle of the engine, and a rheostat controlling the currentthrough said field winding and electromagnetic controlling device.

11. In combination, a prime motor, a load shaft, a variable-speed powertransmission mechanism interconnecting said prime mo tor and load shaft,a controller for varying the speed ratio of said mechanism, a generatordriven by the prime motor, a battery and motor in the circuit of saidgenerator,

gearing connection between said motor and said controller, and a contactin said circuit closed by said controller except when it is in theneutral position.

12. In combination, a prime motor, a load shaft, a variable speed powertransmission mechanism interconnecting said prime motor and load shaft,a"controller for varying thespeed ratio of said mechanism, a generatordriven by the prime motor, a field winding for said generator, a batteryand motor in the circuit of said. generator, a contact in said circuitclosed by said controller except when it is in the neutral position, arheostat in the circuit of said field winding and a contact in parallelwith the contact in the controller closed in the operation of said tionengine, a load shaft, a variable speed power transmission mechanisminterconnecting sa'id'engine and load shaft, a controller for varyingthe speed ratio of said transmission mechanism, means for automaticallyactuating said controller to maintain the output of the engine constant,an lndependent source of energy, and means actuated by controller is inparticular positions.

15. In combination, a prime motor, a load shaft, variable speed powertransmission mechanism interconnecting said prime motor and load shaft,a controller for varying the speed ratio of said mechanism, means foroperating said controller automatically so as to maintain the primemotor at substantially constant speed, a master controller for alteringthe speed at which the prime motor is maintained, a clutch to disengagesaid prime motor from the load shaft, and

tor and load shaft, a controller for varying the speed ratio of saidmechanism, means for actuating the controller automatically,

a clutch for joining said prime motor and load shaft to eliminate saidmechanism, and means interconnecting said clutch and controller so thatsaid clutch can only be in operation for certain positions of saidcontroller.

17 In'combination, a prime motor, a load shaft, variable speed powertransmission mechanism interconnecting said prime motor and load shaft,a controller for varying the speed ratio of said mechanism, means foroperating said controller automatically, an independent energyreservoir, and means actuated by said controller for storing the energyof said prime motor in said reservo1r. v In testimony whereof I havesigned my name to this specification in the presence of two subscribingWitnesses.

J. G. THOMAS.

Witnesses:

KEN. J. THOMSON, A. E. ODELL.

